there's a lot of different opinions as to what exactly constitutes MNT

There's two different discussions here. One is the specific form the technology will take. The other is what it will be capable of doing. About the latter, the idea is to have a technology that will be able to construct things at only marginally higher cost than that of raw materials. If MNT is possible, it will be able to turn dirt into strawberries, coal into diamonds, sand into computers and solar panels, and metal ore into rocket engines. Note that we are capable of accomplishing all of these feats right now; it's just that they take too much time and effort. The promise of MNT and why it is so tantalizing is precisely because it promises, once functional, to reduce this time and effort substantially.

I'm more than willing to debate about the specifics of the technology, although we will both have to admit that any such discussion would be incredibly premature at this point. I don't think a convincing case can be made right now for or against any hypothetical technology that will be able to achieve MNT.

I'm also more than willing to debate about the fundamental physical limits of construction at the nanoscale, but in that case it is much harder to refute the premise of MNT.